Although Celtic's failure to qualify for the Champions League in the last two seasons may have dented the club's finances - and ultimately saw Ronny Deila step down - a record shirt sponsorship deal with Dafabet is set to bring in around £2.65m per year for the four years.

In addition, the promotion of Rangers to the Scottish Premier League is expected to bring in around £10m of additional revenue to their Old Firm rivals, allowing the Scottish champions to offer up the large transfer fund.

But Keane - who finished his career at Celtic Park in 2006 - will understand that Champions League qualification next season is essential if he does take the job and is given the substantial war-chest he is reportedly ready to receive.